Vectorisation of agrochemicals via amino acid carriers: influence of the spacer arm structure on the phloem mobility of phenylpyrrole conjugates in the Ricinus system: Vectorization of agrochemicals via amino acid carriers in the Ricinus system

International audienceBACKGROUND: Excessive agrochemical use causes significant threats to environmental safety and human health. Reducing pesticide use without reducing yield is necessary for sustainable agriculture. Therefore we developed a vectorization strategy to enhance agrochemical delivery through plant amino acid carriers.RESULTS: In addition to a fenpiclonil conjugate recently described, three new amino acid conjugates were synthesized by coupling fenpiclonil to an L-α-amino acid. Phloem mobility of these conjugates which exhibit different structures of the spacer arm introduced between fenpiclonil and the α-amino acid function, was studied using the Ricinus model. Conjugate L-14 which contains a triazole ring with the shortest amino acid chain showed the best phloem systemicity among the four conjugates. By contrast, removing the triazole ring in the spacer arm did not improve systemicity. L-14 exhibited phloem systemicity at all reported pH values (pHs from 5.0 to 6.5) of the foliar apoplast, while acidic derivatives of fenpiclonil were translocated only at pH values near 5.0.CONCLUSION: The conjugates were recognized by a pH-dependent transporter system and translocated at distance in the phloem. They exhibited a broader ability to phloem systemicity than fenpiclonil acidic derivatives within the pH value range of the foliar apoplast